The cancer cell is characterized by its loss of growth control, loss of intercellular adhesiveness and altered antigenicity. These aberrant properties of neoplastic cells evolve, in part, from alterations at/in the plasma membrane. Structural and/or topological alterations of plasma membrane glycoproteins, temporally related to malignant transformation, have been demonstrated. This project will investigate changes in the numerical complexity and/or structure of plasma membrane glycoproteins from normal rat hepatocytes and ascites hepatoma (Novikoff and AS-30D) cells. A radioactive label will be introduced into the oligosaccharide moieties of plasma membrane glycoproteins. Glycoproteins will be extracted and resolved by affinity chromatography on carrier-bound lectins and polyacrylamide gel electrophoresis. Structural alterations in the oligosaccharide moieties of the glycoproteins will be probed by assay of their lectin receptor activities. Those lectins which exhibit the highest specificity for agglutination of tumor cells, i.e. concanavalin A, wheat germ agglutinin and an agglutinin from Ricinus communis will be utilized. Those glycoproteins possessing potent and/or specific lectin receptor activities will be submitted to partial chemical or enzymatic degradation to ascertain the molecular requirements for lectin binding. These investigations will contribute to the elucidation of those plasma membrane alterations relevant to neoplastic transformation, and thereby provide a rational basis for the development of new approaches to immuno- and chemotherapy of cancer.